What is a pool pump?
Updated August 2026
A pool pump is the electric motor and impeller that pull water out of the skimmer and main drain, push it through the filter and heater, and send it back through the return jets. Nothing else on the equipment pad works without it: the filter cannot strain water it never receives, the heater will not fire without proven flow, and chlorine sits in one corner instead of reaching the whole pool. On most homes with a pool, this single motor is the largest electricity user on the property.
Where it is
Look on the equipment pad for the squat unit closest to the water: a motor can bolted to a plastic wet end, with a clear or opaque lid over a strainer basket on top. Two pipes meet it, suction from the skimmer and main drain on one side, discharge to the filter on the other. The data plate on the motor lists horsepower, service factor, and voltage, and on a variable-speed model a small keypad sits on the back of the motor housing.
What it does
The pump moves the entire pool volume through the filter once or twice a day, which is what keeps water clear and chemically even. A 20,000-gallon pool with a 60 gallon-per-minute pump turns over in about six hours. Stop that flow in warm weather and algae appears within 24 to 72 hours, and clearing a green pool costs $150 to $400 in chemicals plus a week of filtering. Dying pumps announce themselves: a bearing screech that grows louder as the motor warms, a drip under the shaft seal, a basket that will not fill because of an air leak at the lid o-ring, or a breaker that trips after 20 minutes of running.
Maintenance
Empty the strainer basket weekly, and twice a week during leaf drop, because a packed basket starves the pump and cooks the seal. Wipe and grease the lid o-ring with silicone each time so it seals without overtightening. Keep the motor vents clear of clippings, and give the pad a full once-over at season open. See how often to service a pool pump, the pool pump maintenance checklist, and pool winterizing for the freeze-season drain. A pump treated that way reaches 8 to 12 years.
What it costs to replace
A replacement pool pump runs $500–1,500 installed, with variable-speed models at the top of that range.
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Frequently asked questions
How many hours a day should a pool pump run?
Aim for one full turnover of the water, then add margin for heat and swimmer load. A single-speed pump usually needs 8 to 12 hours a day in summer and 4 to 6 in the off-season. A variable-speed pump does better run 12 to 24 hours at 1,200 to 1,800 RPM, because slow filtering is quieter, gentler on the filter, and still cheap. Split the run time into two blocks if your pool collects a lot of surface debris.
Is a variable-speed pool pump worth the extra money?
For a pool that runs daily in season, yes. Federal efficiency rules that took effect in 2021 pushed most large single-speed pumps off retail shelves, and the physics behind the rule is the reason: cutting pump speed in half drops power draw far more than half. Owners who swap a 1.5 horsepower single-speed for a variable-speed model commonly see pool electricity fall by several hundred dollars a year, paying back the $700 to $1,500 upgrade in roughly two to four seasons.
Why does my pool pump keep losing prime?
Losing prime means air is entering the suction side. Check four suspects in order: a low water level that lets the skimmer gulp air, a cracked or loose pump lid o-ring, a stuffed strainer basket, and a leaking suction-side valve or union. Fill the basket with water, tighten the lid by hand only, and watch through the clear lid while the pump runs. Swirling bubbles point to a leak; a hard, clear column of water means you are sealed.